For example, a commutator motor is applied to a fuel pump that supplies fuel from a fuel tank into an internal combustion engine. The fuel pump has a pump device for pressurizing fuel drawn from the fuel tank and discharging into the engine. In such a fuel pump, it is necessary to secure torque for rotating a rotor of the fuel pump in order to enhance discharged fuel in amount and pressure. According to US2003/0202893A1 (JP-A-2004-28083), a fuel pump has a center core and a coil core that are individually provided. In this structure, density of the winding can be increased, so that torque generated by a fuel pump can be enhanced while the device body is restricted from being jumboized.
In the structure disclosed in U.S.'893, the fuel pump includes a motor having a commutator that is constructed of multiple segments. The segments make contact with a brush, and electricity supplied to the commutator is intermitted. In this structure, the brush and the commutator are apt to cause electric discharge therebetween due to a residual current when the brush is released from the commutator. When the brush and the commutator cause electric discharge therebetween, the brush and the commutator may electrically cause abrasion. Consequently, operating life of the brush and the commutator may be reduced.